Re: [mpls] New Version Notification for draft-mirsky-mpls-bfd-bootstrap-clarify-00.txt

Greg Mirsky <gregimirsky@gmail.com> Thu, 22 March 2018 21:15 UTC

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From: Greg Mirsky <gregimirsky@gmail.com>
Date: Thu, 22 Mar 2018 21:14:40 +0000
Message-ID: <CA+RyBmUBCFo=hJWa=ozORP01U0jDo9ogBQZMR5qY8964CHNzbg@mail.gmail.com>
Subject: Re: [mpls] New Version Notification for draft-mirsky-mpls-bfd-bootstrap-clarify-00.txt
To: "Carlos Pignataro (cpignata)" <cpignata@cisco.com>
Cc: "Reshad Rahman (rrahman)" <rrahman@cisco.com>, mpls@ietf.org, "rtg-bfd@ietf.org" <rtg-bfd@ietf.org>
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Hi Carlos,
if the group agrees that I'm overparanoid I'll accept that and forever hold
my peace.

Regards, Greg

On Thu, Mar 22, 2018, 7:00 PM Carlos Pignataro (cpignata) <
cpignata@cisco.com> wrote:

> Hi, Greg,
>
>
>
> That, to me, reads like over-specifying. Are you aware of any
> implementation attempting to do that?
>
>
>
> There’s no text for that comparison – why would an implementation do that?
>
>
>
> Thanks,
>
>
>
> Carlos.
>
>
>
> *From: *Greg Mirsky <gregimirsky@gmail.com>
> *Date: *Thursday, March 22, 2018 at 12:18 PM
> *To: *"Reshad Rahman (rrahman)" <rrahman@cisco.com>
> *Cc: *Carlos Pignataro <cpignata@cisco.com>om>, "mpls@ietf.org" <
> mpls@ietf.org>gt;, "rtg-bfd@ietf.org" <rtg-bfd@ietf.org>
> *Subject: *Re: [mpls] New Version Notification for
> draft-mirsky-mpls-bfd-bootstrap-clarify-00.txt
>
>
>
> Hi Reshad,
>
> your analysis of the text is absolutely correct. My concern is the
> possible analysis of the Discriminator by ingress LER and it comparing to
> My Discriminator of the received BFD control packets. According to the RFC
> 5884 both must match but because LSP Echo reply does not provide sufficient
> information the most likely outcome will be - no matching BFD session found
> and thus the text fails. (Yes, it would be rather naive implementation but
> ...). Thus I propose to add explicit statement for ingress LER not to use
> information if received Discriminator TLV in Echo reply.
>
>
>
> Regards,
>
> Greg
>
>
>
> On Thu, Mar 22, 2018 at 3:39 PM, Reshad Rahman (rrahman) <
> rrahman@cisco.com> wrote:
>
> Hi,
>
>
>
> In the BFD meeting yesterday there was discussion about lack of clarity on
> what the spec says wrt to the discriminator TLV being sent by the egress
> node in the echo reply and that this causes interop issues. From RFC 5884:
>
>
>
> The egress LSR MAY respond with an LSP Ping Echo
>
>    reply message that carries the local discriminator assigned by it for
>
>    the BFD session.
>
>
>
> In the errata:
>
> The LSP Ping
>
> Echo reply message generated by the egress LSR MAY carry the local
>
> discriminator assigned by it for the BFD session, as specified in
>
> section 6.1.
>
> So I think it’s clear that this cannot be the discriminator of the ingress
> node. I agree that this information is useless but still don’t see how it
> can cause any harm, and any implementation which interprets the
> discriminator in the echo reply differently is buggy IMHO.
>
>
>
> Regards,
>
> Reshad (hat off).
>
>
>
> *From: *Rtg-bfd <rtg-bfd-bounces@ietf.org> on behalf of "Reshad Rahman
> (rrahman)" <rrahman@cisco.com>
> *Date: *Tuesday, March 20, 2018 at 5:49 PM
> *To: *Greg Mirsky <gregimirsky@gmail.com>om>, "Carlos Pignataro (cpignata)" <
> cpignata@cisco.com>
>
>
> *Cc: *"mpls@ietf.org" <mpls@ietf.org>rg>, "rtg-bfd@ietf.org" <
> rtg-bfd@ietf.org>
> *Subject: *Re: [mpls] New Version Notification for
> draft-mirsky-mpls-bfd-bootstrap-clarify-00.txt
>
>
>
> Hi,
>
>
>
> While I agree that the echo reply is not needed to bootstrap BFD, and that
> the BFD Disc TLV is not needed in the reply, doing this doesn’t break
> anything. So I don’t see the proposed changes as being necessary.
>
>
>
> Does anyone remember why RFC5884  has the echo reply, was it to
> potentially save an echo request from egress for bidirectional case?
>
>
>
> Also, if we do go ahead with the proposed changes in this draft, we’ll
> have to fix this errata <https://www.rfc-editor.org/errata/eid5085>.
>
>
>
> Regards,
>
> Reshad (speaking as individual contributor).
>
>
>
> *From: *Rtg-bfd <rtg-bfd-bounces@ietf.org> on behalf of Greg Mirsky <
> gregimirsky@gmail.com>
> *Date: *Friday, October 20, 2017 at 4:19 PM
> *To: *"Carlos Pignataro (cpignata)" <cpignata@cisco.com>
> *Cc: *"mpls@ietf.org" <mpls@ietf.org>rg>, "rtg-bfd@ietf.org" <
> rtg-bfd@ietf.org>
> *Subject: *Re: [mpls] New Version Notification for
> draft-mirsky-mpls-bfd-bootstrap-clarify-00.txt
>
>
>
> Hi Carlos,
>
> thank you for taking interest in the proposal, much appreciated. Please
> find my notes in-line and tagged GIM>>.
>
>
>
> Regards,
>
> Greg
>
>
>
> On Fri, Oct 20, 2017 at 5:54 AM, Carlos Pignataro (cpignata) <
> cpignata@cisco.com> wrote:
>
> Greg,
>
>
>
> This document seems to say “use “Do not Reply” reply mode, and even if you
> reply do not use the BFD Disc TLV, because it is not used.
>
> GIM>> To be precise it says "SHOULD use "Do not Reply" thus preserving
> compliance of implementations that do otherwise.
>
>
>
> Wouldn’t it be simpler to say “follow RFC 8029, and the ingress does not
> care about the BFD Disc TLV in the reply”? This would not suddenly make
> uncompliant existing implementations, potentially.
>
> GIM>> I agree that normative language on handling echo reply is bit
> restrictive. My goal is to have good discussion and see what others think.
>
>
>
> Also I wonder if this should be bfd-mpls instead of mpls-bfd, given where
> RFC 5884 was advanced.
>
> GIM>> Probably it should be the way you've suggested. Hope it is not a big
> problem for individual draft.
>
>
>
> Thanks,
>
>
>
> —
> Carlos Pignataro, carlos@cisco.com
>
> *“Sometimes I use big words that I do not fully understand, to make myself
> sound more photosynthesis."*
>
>
>
> On Oct 18, 2017, at 8:50 AM, Greg Mirsky <gregimirsky@gmail.com> wrote:
>
>
>
> Dear All,
>
> this new document proposes clarification of two questions brought up in
> course of recent discussion of RFC 5884:
>
>    - use of Return mode values in bootstrapping BFD session echo request;
>    - inclusion of BFD Discriminator TLV in echo response to the
>    bootstrapping echo request.
>
> Your comments, questions are always welcome and greatly appreciated.
>
>
>
> Regards,
>
> Greg
>
>
>
> ---------- Forwarded message ----------
> From: <internet-drafts@ietf.org>
> Date: Wed, Oct 18, 2017 at 5:46 AM
> Subject: New Version Notification for
> draft-mirsky-mpls-bfd-bootstrap-clarify-00.txt
> To: Gregory Mirsky <gregimirsky@gmail.com>om>, Yanhua Zhao <
> zhao.yanhua3@zte.com.cn>
>
>
>
> A new version of I-D, draft-mirsky-mpls-bfd-bootstrap-clarify-00.txt
> has been successfully submitted by Greg Mirsky and posted to the
> IETF repository.
>
> Name:           draft-mirsky-mpls-bfd-bootstrap-clarify
> Revision:       00
> Title:          Clarifying Use of LSP Ping to Bootstrap BFD over MPLS LSP
> Document date:  2017-10-18
> Group:          Individual Submission
> Pages:          4
> URL:
> https://www.ietf.org/internet-drafts/draft-mirsky-mpls-bfd-bootstrap-clarify-00.txt
> Status:
> https://datatracker.ietf.org/doc/draft-mirsky-mpls-bfd-bootstrap-clarify/
> Htmlized:
> https://tools.ietf.org/html/draft-mirsky-mpls-bfd-bootstrap-clarify-00
> Htmlized:
> https://datatracker.ietf.org/doc/html/draft-mirsky-mpls-bfd-bootstrap-clarify-00
>
>
> Abstract:
>    This document, if approved, updates RFC 5884 by clarifying procedures
>    for using MPLS LSP ping to bootstrap Bidirectional Forwarding
>    Detection (BFD) over MPLS Label Switch Path.
>
>
>
>
> Please note that it may take a couple of minutes from the time of
> submission
> until the htmlized version and diff are available at tools.ietf.org.
>
> The IETF Secretariat
>
>
>
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